Method of producing an aerofoil having a core and a laminated molded skin

ABSTRACT

656,020. Aerofoils. NATIONAL RESEARCH DEVELOPMENT CORPORATION. June 11, 1948, No. 15855. [Class 4] [Also in Group VIII] An aerofoil or other article having a laminated skin of moulded synthetic resinous material secured to an inner structure or core is made by interposing a parting agent between the whole or part of an outer lamination 11 of the skin and the whole or part of a next adjacent lamination 16, moulding the skin to shape, displacing the whole or part of the outer lamination, securing the skin to the inner structure or core 23 by securing members such as screws 24 which pass through the inner laminations of the skin, and replacing and glueing down the outer lamination. Alternatively, the planes of weakness may be so produced in the moulding stage that the whole of the leading edge L, Fig. 5, comes away with the outer skin when it is separated from the rest of the moulding. The parting agent may be a sheet of regenerated cellulose or a coating of methyl cellulose. The assembly placed in a mould 12 may comprise a layer 11 of uncured asbestos-reinforced synthetic resinous material, a thin layer 13 of glass fibre cloth, a layer 14 of regenerated cellulose, and a further layer 15 of glass fibre cloth, and sufficient further layers 16 of resin-treated asbestos to make up the required thickness. A porous mat 20 of glass fibre-cloth carrying an embedded electrical resistance network is placed in contact with the assembly, and is followed by a rubber bag 22 which is evacuated prior to heating by heat from the resistance networks and, if desired, from the mould itself.

J E. GORDON ET AL y OF PRODUCING AN AEROFOIL HAVING E AND A LAMINATED MOLDED SKIN 2 Sheets-Sheet l Oct. 13, 1953 METHOD A coR ruled May 31 1949 0d. 13, 1953 J. E. GORDON ET AL METHOD oF PRoDucrNG AN AERoFoIL HAVING A CORD AND A LAMINATED MOLDED SKIN 2 sheets-sheet 2 Filed May 3l, 1949 f erden C G Evans inve/liar;

Attorney;

Peienied oei. i3, i953 l l 2 655 459 METHOD OF PRODUCING AN AEROFOIL HAVING A CORE AND A LAMINATED KIN James E. Gordon, Rollrlght, Fleet, and Cyril G. Evans, Farnborough, England, assignors to the 'nster of Supply in His Majestys Government of the United Kingdom of Great Britain and Northern Ireland, London, England Application May 31, 1949, Serial N o. 96,234 L In Great Britain June 11, 1948 8 Claims. (Cl. 154-110) articles having skins of moulded material, for extioned in a mould I2 o1' the requisite shape and ample of moulded plastic material such as is followed by a thin layer I3 of glass libre cloth, thermo-setting synthetic resinous products. a layer I 4 ofregenerated cellulose and a further ere re-inforcing space-dividing and other e layer I5 of glass libre cloth, after which suliicient internal members are secured to a skin by screws, further layers of curable synthetic resinous mateticularly the case in connection with aerofoil Sand I9. Aporous mat 20 of glass libre cloth,in

outer surface of the skin is exposed to the airbedded, is placed in contact with the last layer flow.

i laminated skin is so moulded that an outer porl5 material is cured by the application of heat from on hereof is dlvided from the remainder by the resistance network and from any electrical or a plane of weakness, after the moulding opera other eating means (not shown) provided in the tion, e outer portion is separated from the remould itself, the material being pressed against mainder portion and nally xed in position the moulding surface by the differential pressure covering any screws, nails or other xing memproduced by the evacuation of the rubber bag by bers which have been inserted means of a vacuum pump or the like The t adequately together and this result may be I5 of glass libre cloth and cellulose offering noA also be costly i'n view of the very high degree of 30 ated cellulose prevents adhesion of the outer of the two portions, this layer may be separated from the rest of An example of the application of the invention the moulded Skin as illustrated by Figure 2. This the production of an aerofoil comprising a figure also shows a wooden rib 23 set up in posimoulded skin secured to wooden ribs is illustrated 0n and Secured by Screws 24 passing through y the accompanying drawings' n W o countersunk holes drilled i t e main portion Figure 1 represents a section through pari; of 0f the moulded skin Finally, any traces oi glass he requis e materials and aooossories assembled libre clo having been removed from the outer n a mould for the erst step in the production of 40 Surface 0f the main Skin moulding and the inner e noso portion of on aerofoii. surface of the outer layer, the outer layer II is Figure 2 represents, in section and to a smaller replaced in Position, aS ShOWIl by Figure 3, and scale, the materials involved in the step following glued t0 the mem mouldinge moulding operati n, In this and succeeding In cases in which it is unnecessary to separate figures, c osshatchi'ng is omitted in the interests 45 the Whole 0f the Outer layer from the main P01" of clarity, tion of the skin moulding. parting agent or agents Figure 3 is a representation in section, similar may be p1' Ovided only between these parte 0f the to that of Figure 2, of the completed nose portion. Outer layer and 0f the main portion which it is lgure 4 s a sectional representation, equiva necessary t0 Separate fOr the pul'DOSe 0f inserting lent to that of Figure 2, of the second step in an 5o the screws or the like. In the case, for example, alternative method of production and of a substantially U-shaped molding for the forgure 5 is a sectional representation, equlvaward portion of the skin of an aerofoil, it may be lent to those of Figures 2 and 4, of the second necessary Only to provide planes 01' Weakness in step of a third method.

the the lirst step, illustrated by Figure l, a layer tion of the sw- L curing process and being undisturbed when the and said next adjacent inner lamination of the rearward portions of the upper and lower layers skin locally thereof, wherein said outer laminaare iiexed away from the remainder, as repretion is undivided, and wherein said inner laminasented in Figure 4, to permit insertion ci the tion, where the parting agent is interposed toscrews or the like. According to the alternative gether with corresponding parts of any further method illustrated by Figure 5, planes of weakinner laminations moulded thereto, is divided ness are so produced in the moulding stage that from the remainder thereof.

the whole of the leading edge portion of the aero- 4. A method of producing an article as claimed foil is not only formed integrally w'th the outer in claim lin which the parting agent is regenskin layer but comes away with it when it is l0 erated cellulose sheet.

separated from the remainder of the moulding: 5. A method of producing an article as claimed this procedure is preferable to that illustrated in claimv l in which the parting agent is regenby Figure 4 when it is required to insert screws or erated cellulose4 sheet with layers of glass nbre the like near the leading edge oi the aeroioil. clQth interpesed between it and the Synthetic 1f desired, the use alone oi pre-.formed solid l5 resinous material. sheets of parting agent in the production of 6. Arnethod of producing an article as claimed planes of weakness may be replaced by the use, in claim l in which the parting agent is applied alone or in conjunction with a, solid sheet of glass by spraying., fibre cloth or the like, of an easily removable 7. A method for producing a shaped article part'ng agent which is sprayed on to the'aces 20 comprising a core and a moulded skin of cured of the uncured material which are to form the synthetic resinous material secured to the core inner surface-of the outer skinlayer and the by securing members extending into the Gere outer surface of the main skin moulding.. Thus, trom. within the skin, of which latter the outera water-soluble parting agent such as methyl surface is shaped to a high degree 0f accuracy. cellulose may be sprayed onto resinated asbestos according to which a first Skin layer 0f Synthetic material before the latter is'positioned in the resinous material isl placed upon the core, there mould, the parting agent being washed orf the are then applied to said rst skin layer first a, faces after curing and before nnal gluing, unless parting material and subsequently a second skin; compatible with the particular glue to be used. layer OS thetic TeSineilS material, the first and We, claim; second skin layers are then simultaneously l. A meth d of producing with a continuous melllded and cured, the second Skin layer iS diS- external surface an article having an inner strucplaced rem the fnSt Skin. layer, Securing memture and a laminated skin oi moulded synthetic bers are inserted through the. first skin layer resinous material secured to said inner structure inte the cerey and, the Second Skin layer iS adE by securing members which extend through the hered to thev ilrst Skin layer. skin into the inner structure, according to which 8. A method for producing a shaped article a parting agent is interposed between an outer comprising a Core and a moulded skin of cured lamination and a next adjacent inner lamination Synthetic reSinOllS material -Seclll'ed t0 the c01e ci the skin, the skin is then moulded to shape, by securing members extending into the core said outer lamination is displaced from said inner 40 from within the Skin of Which latter the Outer. lamination where the parting agent is interposed Surface is shaped to a high degree 0f accuracy, between them, the skin is secured to an inner aCCOrding to which a first skin layer 0f Synthetic structure by passing securing members through resinous material is placed upon the Cere, there said inner but not said outer lamination into said are t en applied t0 ,Said fllSt Skin layer filSt a inner structure and said outer lamination is re- 4D parting material locally thereof and subsequentplaced to said inner lamination and caused to ly a Second Skin layer Of. Synthetic IeSinOuS ma'. adhere thereto, terial covering the rst skin layer, the first and 2. A method of producing with a continuous Second skin layers are thensimultaneously external surface an aerofoil or other article havo moulded and cured, the second skin layer is dis-VI ing a core and a laminated skin of moulded synd placed from the first skin layer Where the parting thetic resinous material secured to said core by material is applied, securing members are insecuring members which extend through the skin serted through the first, skin layer Where the See into said core, according to which a parting agent 0nd Skin layer is displaced from it intO the Cere is interposed between an outer lamination and andy the Second Skin layer is adhered to the. nist a next adjacent inner lamination of the skin Skinlcyelbeing sufficiently thin and of such a nature that Y JAMES E- GORDON- the inner surface of the outer lamination will be CYRlL Gf EVANS substantially of. the same shape and configura tion as the outer surface of the inner lamination, References Cited in the file 0f this Pietel-1i#wv the skin is then moulded to shape, 'said outer i UNITED STATES PATENTS lamination is displaced from said inner lamina- Number Name Date tion where the parting agent is interposed bei 1,980,022 Whitehouse 'NOV 6 1934 tween them, the skin is secured to a coreV by pass- 2,070,023 Olsen Feb.' 9: 1937 -g securing members through said inner but not 2,310,619 Dillenay Feb, 9, 1943' said outer lamination into the core, and said 2,431,720 Willey De@ 2 1947 outer lamination is replaced to said inner laminal 1 J tion and caused to adhere thereto. FOREIGN PATENTS 3. A `method as claimed in claim l wherein the Numbei Cellntry Date parting agent is interposed between said outer 271,192 Great Britain 2...., May 26, 1921l 

1. A METHOD OF PRODUCING WITH A CONTINUOUS EXTERNAL SURFACE AND ARTICLE HAVING AN INNER STRUCTURE AND A LAMINATED SKIN OF MOULDED SYNTHETIC RESINOUS MATERIAL SECURED TO SAID INNER STRUCTURE BY SECURING MEMBERS WHICH EXTEND THROUGH THE SKIN INTO THE INNER STRUCTURE, ACCORDING TO WHICH A PARTING AGENT IS INTERPOSED BETWEEN AN OUTER LAMINATION AND A NEXT ADJACENT INNER LAMINATION OF THE SKIN, THE SKIN IS THEN MOULDED SYNTHETIC SAID OUTER LAMINATION IS DISPLACED FROM SAID INNER LAMINATION WHERE THE PARTING AGENT IS INTERPOSED BETWEEN THEM, THE SKIN IS SECURED TO AN INNER STRUCTURE BY PASSING SECURING MEMBERS THROUGH SAID INNER BUT NOT SAID OUTER LAMINATION INTO SAID INNER STRUCTURE AND SAID OUTER LAMINATION IS REPLACED TO SAID INNER LAMINATION AND CAUSED TO ADHERE THERETO. 